2-(5,6-Dihydrobenzimidazo[1,2-c]quinazolin-6-yl)phenol

The asymmetric unit of the title compound, C20H15N3O, contains two independent molecules, each of which is disordered over two sets of sites corresponding to a rotation of approximately 180° of the dihydrobenzimidazoquinazoline moiety, with refined site occupancies of 0.7479 (13) and 0.2521 (12) for both molecules. The pyrimidine rings are in sofa conformations. In one molecule, the hydroxy-substituted benzene ring forms dihedral angles of 83.9 (3) and 82.4 (4)° for the major and minor components, respectively, with the mean plane of the benzimidazole ring system. The corresponding dihedral angles in the other molecule are 88.31 (14) and 85.8 (6)°. In the crystal, molecules are linked via intermolecular O—H⋯N and N—H.·O hydrogen bonds into chains along [100].

The asymmetric unit contains two independent molecules ( Fig. 1), A and B. In each molecule, the benzimidazole fused ring system is disordered over two sets of sites with refined site occupancies of 0.748 (1) et al., 1987) and angles are within normal ranges.

Experimental
The title compound was synthesized using Taha-Teoh's method (Eltayeb et al., 2011). To a solution of 2-(2-aminophenyl)-1H-benzimidazole (0.209 g, 1.0 mmol) in ethanol (30 mL) was added 2-hydroxybenzaldehyde (0.1 mL, 1.0 mmol). The color of the resulting solution is pale-yellow. Then on adding zinc chloride (0.136 g, 1.0 mmol), the color of the solution became golden-yellow. The mixture was refluxed with stirring for 3 h. Crystals suitable for XRD were formed after several days of slow evaporation of ethanol at room temperature.

Refinement
The title compound is disordered over two positions with refined site-occupancies of 0.748 (1)

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (